i2c: i801: improve interrupt handler

Not sure if it can happen, but better play safe: If SMBHSTSTS_BYTE_DONE
and an error flag is set, then don't trust the result and skip calling
i801_isr_byte_done(). In addition clear status bit SMBHSTSTS_BYTE_DONE
in the main interrupt handler, this allows to simplify the code a
little.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 1fda1ea..da773c5 100644 (file)
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -558,9 +558,6 @@ static void i801_isr_byte_done(struct i801_priv *priv)
                /* Write next byte, except for IRQ after last byte */
                outb_p(priv->data[++priv->count], SMBBLKDAT(priv));
        }
-
-       /* Clear BYTE_DONE to continue with next byte */
-       outb_p(SMBHSTSTS_BYTE_DONE, SMBHSTSTS(priv));
 }
 
 static irqreturn_t i801_host_notify_isr(struct i801_priv *priv)
@@ -590,7 +587,6 @@ static irqreturn_t i801_host_notify_isr(struct i801_priv *priv)
  *      BUS_ERR - SMI# transaction collision
  *      FAILED - transaction was canceled due to a KILL request
  *    When any of these occur, update ->status and signal completion.
- *    ->status must be cleared before kicking off the next transaction.
  *
  * 2) For byte-by-byte (I2C read/write) transactions, one BYTE_DONE interrupt
  *    occurs for each byte of a byte-by-byte to prepare the next byte.
@@ -615,23 +611,18 @@ static irqreturn_t i801_isr(int irq, void *dev_id)
        }
 
        status = inb_p(SMBHSTSTS(priv));
-       if (status & SMBHSTSTS_BYTE_DONE)
+       if ((status & (SMBHSTSTS_BYTE_DONE | STATUS_ERROR_FLAGS)) == SMBHSTSTS_BYTE_DONE)
                i801_isr_byte_done(priv);
 
        /*
-        * Clear remaining IRQ sources: Completion of last command, errors
-        * and the SMB_ALERT signal. SMB_ALERT status is set after signal
-        * assertion independently of the interrupt generation being blocked
-        * or not so clear it always when the status is set.
-        */
-       status &= SMBHSTSTS_INTR | STATUS_ERROR_FLAGS | SMBHSTSTS_SMBALERT_STS;
-       if (status)
-               outb_p(status, SMBHSTSTS(priv));
-       status &= ~SMBHSTSTS_SMBALERT_STS; /* SMB_ALERT not reported */
-       /*
-        * Report transaction result.
-        * ->status must be cleared before the next transaction is started.
+        * Clear IRQ sources: SMB_ALERT status is set after signal assertion
+        * independently of the interrupt generation being blocked or not
+        * so clear it always when the status is set.
         */
+       status &= STATUS_FLAGS | SMBHSTSTS_SMBALERT_STS;
+       outb_p(status, SMBHSTSTS(priv));
+
+       status &= STATUS_ERROR_FLAGS | SMBHSTSTS_INTR;
        if (status) {
                priv->status = status;
                complete(&priv->done);